<?php
$person = array (
    "name" => "Alex",
    "age" => "28",
    "location" => array (
        "Greenwich" => array (
            "New Eltham",
            "Central Greenwich"
        ),
    "Feltheam"
    )
);

$person[$localtion][$Greenwich][2] = "Outer Greenwich";

echo '<pre>', print_r($person,true), '</pre>';

?>
